During the last seven years, my research has been directed toward elucidating the neuronal mechanisms involved in visual pattern recognition and perception: these mechanisms seem to be the mainstays of brain function, at any phylogenetic level. There are three distinct, yet interdependent, aspects of this work. The first has to do with the identification of functions in structures that are implicated in vision, to sharpen what is known about the "flow diagram" of the system. The second aspect has investigated at the single unit level the way in which non-visual brain structures inject information or affect transmission of information in the visual pathway, i.e., that intersensory integration which, I think, builds a perceptually constant visual world. Finally, the third aspect has involved an in-depth analysis of the visual pathway form the retina of the eye to the visual cortex at the single unit level. Major accomplishments have been: first, development of automated techniques which enabled us to study the receptive fields of single cells in an objective, quantitative and highly precise manner; second, the demonstration that non-visual sensory systems have powerful influences in the visual pathway at all levels and as far peripherally as the retina; third, some real progress has been made in understanding the genesis and significance of receptive field shapes in single units of the cat's visual cortex. This proposal, a logical outcome and synthesis of the above, deals with moving from single unit to system analysis by collecting data from more than one unit simultaneously, crucially optimizing stimulus presentation procedures, and testing the behavioral significance of units of a given class and of networks of units.